I assume the kid does not have a father in his life, or at least not one who attends his games. I would have had a violent reaction if I witnessed an adult doing that, even if the victim was not my child. Even as a coach, I would have had “words” with the offender until the police arrived.
After the article played on the local news, i turned and mused to my wife,"Why didn't other parents at the game, particularly fathers, respond in a less than charitable fashion to this man?" If people new there were going to be immediate societal repercussions for their assinine actions perhaps they would think twice about acting.
It was the kid’s father who tripped the other kid, I believe.